const table = document.querySelector('table')
const colNum = 26
const rowNum = 48
function renderTableHeader() {
  const col = new Cols(colNum)
  const thead = document.createElement('thead')
  const tr = document.createElement('tr')
  col.ths.forEach(it => {
    tr.appendChild(it)
  })
  thead.appendChild(tr)
  table.appendChild(thead)
}
renderTableHeader()
function renderTableBody() {
  const tbody = document.createElement('tbody')
  for (let i = 0; i < rowNum; i++) {
    const tr = document.createElement('tr')
    const idxTd = document.createElement('td')
    idxTd.innerHTML = i
    tr.appendChild(idxTd)
    for (let j = 0; j < colNum; j++) {
      const td = new Cells(i, String.fromCharCode(65 + j))
      tr.appendChild(td.dom)
    }
    tbody.appendChild(tr)
  }
  table.appendChild(tbody)
}
renderTableBody()
